This invention relates to a low emissivity (low-E) coating system including diamond-like carbon (DLC) provided on (directly or indirectly) a substrate of glass, plastic, ceramic, or the like, and a method of making the same.
Sputter coated systems for deposition on glass are known in the art for achieving solar management properties in glass articles such as insulating glass (IG) windows, vehicle windows, and the like. In many such coating systems, it is desirable to provide a coating system capable of: (i) reflecting a certain amount of infrared (IR) radiation, while (ii) allowing an acceptable amount of visible light transmittance, and (iii) limiting the amount of visible light reflectance off of the coating system.
Exemplary low-E coating systems are disclosed in U.S. Pat. Nos. 5,800,933; 5,770,321; 5,419,969; and 5,344,718, the disclosures of which are all hereby incorporated herein by reference.
Unfortunately, many conventional low-E coating systems are prone to scratching. Thus, they are not as abrasion resistant as would be desired. Because of this potential for scratching, many low-E coating systems are not typically utilized in applications such as rear vehicle windows (e.g., back seat vehicle windows, vehicle backlites, etc.). Instead, such windows are often tinted in order to keep IR rays out of the vehicle (which also has the effect of reducing visibility in certain circumstances).
U.S. Pat. No. 5,976,683 discloses a coating system having high transmissivity in the visible spectrum and high reflectivity in the thermal radiation spectrum. A polycrystalline carbon layer crystallized with a diamond structure and doped with foreign atoms is provided and formed via CVD. Unfortunately, such polycrystalline layers are difficult and expensive to deposit on substrates and typically require very high temperatures during the deposition process (e.g., from 700 to 1,000 degrees C.). If one attempted to elevate a substrate including a low-E coating system thereon to such temperatures, many such low-E systems would be destroyed or significantly damaged. Thus, the use of a polycrystalline diamond layer formed in such a manner over a low-E system is neither practical nor desirable.
In view of the above, it will be apparent to those skilled in the art that there exists a need in the art for an improved scratch resistant and/or mechanically durable low-E coating system for use in automotive and/or architectural window applications. There also exists a need in the art for a low-E coating system that can repel water and/or dirt, and a method of making the same. There also exists a need in the art for a low-E coating system including a protective layer(s) system that can be deposited over underlying low-E layers via a low temperature process.
It is a purpose of different embodiments of this invention to fulfill any or all of the above described needs in the art, and/or other needs which will become apparent to the skilled artisan once given the following disclosure.
An object of this invention is to provide a low-E coating system that is scratch resistant and mechanically durable.
Another object of this invention is to provide a diamond-like carbon (DLC) inclusive protective layer(s) or coating system located over a low-E layer arrangement, wherein the DLC inclusive protective layer(s) or coating system can be deposited in or via a low temperature process so as to not significantly damage the existing or underlying low-E layer arrangement.
Another object of this invention is to provide a low-E coating system that is (i) scratch resistant and mechanically durable, (ii) capable of reflecting an acceptable amount of infrared (IR) radiation, (iii) capable of allowing an acceptable amount of visible light transmittance, and (iv) capable of limiting the amount of visible light reflectance off of the coating system.
While non-hydrophobic low-E coating systems are often desirable, there also sometimes exists a need in the art for a low-E coating system that may be hydrophobic (i.e., can shed or repel water) if desired. Thus, another object of this invention is to provide low-E coating systems that are hydrophobic, as well as low-E coating systems that need not be hydrophobic.
Another object of this invention is to provide a scratch resistant low-E coating system including at least one diamond-like carbon (DLC) inclusive layer having at least some highly tetrahedral amorphous carbon (ta-C), wherein the ta-C includes sp3 carbonxe2x80x94carbon bonds so as to make the layer more scratch resistant and mechanically durable.
In certain embodiments, a low-E coating system may include each of a DLC inclusive layer(s) and a fluoro-alkyl silane (FAS) compound inclusive layer, wherein the DLC is provided for durability purposes and the FAS for increasing the contact angle xcex8 of the coating system.
Another object of certain embodiments of this invention is to provide a low-E coating system including sp3 carbonxe2x80x94carbon bonds and FAS, the low-E coating system having a wettability W with regard to water of less than or equal to about 23 mN/m, more preferably less than or equal to about 21 mN/m, even more preferably less than or equal to about 20 mN/m, and in most preferred embodiments less than or equal to about 19 mN/meter. This can also be explained or measured in Joules per unit area (mJ/m2)
Another object of this invention is to provide a low-E coating system having a surface energy xcex3C (on the surface of the coated article) of less than or equal to about 20.2 mN/m, more preferably less than or equal to about 19.5 mN/m, and most preferably less than or equal to about 18 mN/m.
Another object of this invention is to provide a low-E coating system having an initial (i.e. prior to being exposed to environmental tests, rubbing tests, acid tests, UV tests, or the like) water contact angle xcex8 of at least about 55 degrees, more preferably of at least about 80 degrees, still more preferably of at least about 100 degrees, even more preferably of at least about 110 degrees, and most preferably of at least about 125 degrees.
Another object of this invention is to manufacture a low-E coating system including at least one DLC inclusive layer, wherein the DLC inclusive layer is deposited in a manner such that during the deposition process the underlying substrate and/or IR reflecting layer (e.g., Ag layer) may be kept at temperature(s) no greater than about 200xc2x0 C., preferably no greater than about 150xc2x0 C., most preferably no greater than about 80xc2x0 C., so as to reduce the likelihood of heat-induced damage to portions of the low-E coating system.
Yet another object of this invention is to fulfill any and/or all of the aforesaid objects and/or needs.
This invention will now be described with respect to certain embodiments thereof, along with reference to the accompanying illustrations.